Republican front-runner praises Corey Lewandowski even as party grandees voice
concern about growing violence at his rallies

Donald Trump praised his campaign manager as “spirited” after footage showed him appearing to grab a protester by the collar amid rising concerns about violence at the Republican frontrunner’s rallies.

Corey Lewandowski was seen getting into a heated argument with a young man at a rally in Tucson, Arizona, on Saturday in video footage that spread rapidly across social media.

It was the second time Mr Lewandowski had faced allegations of violence in just over a week following accusations that he manhandled a female reporter as she was trying to ask Mr Trump a question while he was campaigning in Florida.

Mr Trump, who has been accused of inciting violence with some of his rhetoric, praised Mr Lewandowski when quizzed about his behaviour on ABC’s This Week programme on Sunday - and instead blamed the episode on “lax security” by police.

“I will give him credit, spirited,” he said. “I give him credit for having spirit. He wanted them to take down those horrible profanity-laced signs.

“Security at the arena, the police were a little bit lax. They had signs up in that area that were horrendous, that I cannot say what they said on the sign.”

A security official motions to escort a an anti-Trump protester to leave before Republican presidential candidate Donald Trump spoke Photo: AP

The footage showed Mr Lewandowski and another man approaching a group of protesters holding placards at Saturday’s rally. The two men confront one of the protesters, who briefly turns his back before being yanked back to face them. Mr Trump insisted it was Mr Lewandowski's accomplice, a member of the candidate's private security detail, who had grabbed the protester, altough the footage suggests otherwise.

Mr Trump declined to take responsibility for the outbreaks of violence at his campaign rallies, instead blaming “professional agitators” whom he said had blocked the road leading to the venue for an earlier rally in Phoenix.

"These are professional agitators, and I think that somebody should say that when a road is blocked going into the event so that people have to wait sometimes hours to get in, I think that's very fair and there should be blame there, too," he said. "These people are very disruptive people. They're not innocent lambs.”

Trump protester Bryan Sanders, center left, is punched by a Trump supporter as he is escorted out of Republican presidential candidate Donald Trump's rally at the Tucson Arena in downtown Tucson Photo: AP

In the second incident, a Trump supporter - an African-American - punched a demonstrator who was being led away by security personnel and then continued to kick and stamp on the man as he lay on the ground. The protester, who had an American flag wrapped around his torso, was accompanied by a friend who was wearing a Ku Klux Klan mask and also being escorted out.

Mr Trump said the assailant had been provoked by the klan mask. “It was a tough thing to watch. And I watched it,” he told the interviewer, George Stephanopoulos. “But why would a protester walk into a room with a Ku Klux Klan outfit on?”